Despite the relative unpopularity of enhanced e-books—which, unlike unenhanced e-books, incorporate interactive features, including audio and video—Chris Kyle’s “enhanced” memoir American Sniper rose to the top of Apple’s iBook bestseller list and remained there for the first three weeks of January. But what does this mean?

According to Publishers Weekly, it could mean that enhanced e-books are a viable market if they tie in with the release of TV and film adaptations.

The enhanced e-book for American Sniper, which includes twelve video interviews with Kyle (before his death in 2013), as well as one video with his wife, Taya Kyle, was released with the hardcover in January 2012, but the film didn’t premiere until this past January. “With the explosion of book sales now that the movie is out and has become a blockbuster, it makes perfect sense that the e-book would be equally in demand again,” said Sharyn Rosenblum, VP, senior director of media relations at HarperCollins.

Indeed, is, HarperCollins CEO Brian Murray says—the enhanced edition has already sold more than 166,000 copies.

But publishers must tread carefully when enhancing e-book content said Penguin Random House’s senior VP, director of digital publishing development, Nina Von Moltke. “[W]e always keep a reader’s interest in mind and are careful not to turn a book into a marketing vehicle for a movie. What seems to work best in the market are editions that provide unique and relevant content.”

Furthermore, there are still some kinks to be worked out before enhanced books really take off, according to Peter Costanzo, an e-book producer, at Digital Book World. “The main problem is that the market as it currently exists does not allow publishers to deliver the same enhanced product across all current digital platforms, whether it be Apple’s iPad, Amazon’s Kindle Fire, Barnes & Noble’s Nook, and Kobo’s Arc,” he wrote.

“If publishers can’t widely distribute enhanced ebooks across all channels, then they will simply never gain traction by word of mouth, reviews, or with promotions.”